Various 1,2-dichlorocyanovinyl compounds are disclosed in the prior art as having antimicrobial properties. Many of these compounds are disclosed in co-pending U.S. patent application Ser. No. 834,215, filed Sept. 19, 1977, now U.S. Pat. No. 4,238,405. Compounds disclosed are those having the general structural formula ##STR2## wherein n is 0, 1, or 2 and R is selected from the group consisting of alkyl, alkylcarbalkoxy, cyclohexyl, halophenyl, benzyl, N,N-di-lower alkyl carbamoyl, hexamethyleneimino carbonyl, pyrimidyl, lower alkyl substituted pyrimidyl, benzimidazole, lower alkyl substituted pyrimidyl, benzimidazole, lower alkyl substituted imidazole, benzothiazole and O,O-di-lower alkyl thiophosphoryl; with the proviso that when n is O, R is other than alkyl or cyclohexyl.